code: def test_leaf(self):
      a = tensor.scalar("a")
      b = tensor.scalar("b")
      c = tensor.scalar("c")
  
      b.tag.replacement = c
  
      u = a + b
      (v,) = map_variables(self.replacer, [u])
  
      assert u.owner.inputs == [a, b]
      assert v.owner.inputs == [a, c]
  
file_path: Theano/theano/scan_module/tests/test_scan_utils.py
imports: from __future__ import absolute_import, print_function, division
  import itertools
  import unittest
  import numpy
  import theano
  from theano import tensor
  from theano.scan_module.scan_utils import equal_computations, map_variables
  from theano.tensor.type_other import NoneConst
label_desc: Use image node_id 2 for calling the TestMapVariables obj's underlying member method code with example usage: obj.test_leaf() without return types